1 Gentoo:Kernel Cleanup
2 =====================
3 :author: Aaron Ball
4 :email: nullspoon@iohq.net
5 :revdate: October 30, 2015
6
7 == {doctitle}
8
9 Gentoo is a source-based Linux distribution. Moreover it's aimed at more
10 advanced users with the intent of not forcing anything on them, as much as is
11 possible with so many packages.
12
13 Normally, whenever you get a kernel update on a distro, say from 4.2.0 to
14 4.2.5, the system does several things.
15
16 * Download the new kernel (pre-compiled)
17 * Install the new kernel
18 * Update the initramfs
19 * Update the bootloader
20 * Clean up the unused kernels
21
22 Gentoo requires that their users to each of those items. I'm fairly new to
23 Gentoo and, coming from Arch Linux, already knew for the most part how to do
24 all of those steps, except for the last one. That said, lets talka bout how to
25 clean up unused kernels on your system.
26
27 == TL;DR Summary
28
29 Here are the locations that need to be cleaned up, in case you want to skip to
30 that section or already know what you're doing but just need the list.
31
32 * emerge -C <sys-kernel/<type>-sources-<version> _(This is specific to Gentoo)_
33 * Files
34 * /usr/src/linux-<versions>
35 * /lib/modules/<versions>
36 * /boot/*-<versions>
37
38
39 == Inventory
40
41 The first step is to take an inventory. The largest part of a kernel in Gentoo
42 is its source code, so we'll look at that for the inventory (there are other
43 ways and we'll look into those as well).
44
45 Gentoo stores its kernel source at _/usr/src/linux-*_. In there, you can see
46 multiple versions of the linux source code. In my case, I have linux-4.2.0 all
47 the way up to linux 4.2.5.
48
49 NOTE: In my case, I'm using vanilla-sources for my kernel, so the directory
50 names for you might be a tad different. Despite though, they should still start
51 with _linux-x.x.x*_.
52
53
54 == Clean Up the Source
55
56 Now that we have an inventory, let's clean up the source. This is very simple.
57 Once you know what versions you want to keep, we can issue an emerge command
58 that will clean up the files for the source. For my example, we'll say we want
59 to remove anything before 4.2.4
60
61 emerge -Cp <sys-kernel/vanilla-sources-4.2.4
62
63 That command will delete any files installed by emerge if they belong to kernel
64 versions 4.2.3 or less. However, it doesn't clean up any files created by the
65 compile process, so we still need to remove those.
66
67 To see where we are first, here's an ls example of my src directory.
68
69 0 [nullspoon@null ~]$ ls /usr/src/
70 linux linux-4.2.0 linux-4.2.1 linux-4.2.2 linux-4.2.3 linux-4.2.4 linux-4.2.4-gentoo linux-4.2.5 linux-4.2.5-gentoo
71
72 Now for a simple but gratifying rm command. Since rm has no knowledge of the
73 kernel versioning scheme, we can't say "less than version 4.2.4" and it'll
74 clean up. In this case, we'll use a simple bash sequence.
75
76 rm -rf /usr/src/linux-4.2.{0,1,2,3}
77
78 NOTE: If you are worried about running that command and what it'll do, run it
79 with echo before it to see what it will output without actually deleting
80 anything.
81
82
83 == Clean up Installed Modules
84
85 The Linux kernel stores its modules in */lib/modules* (fun fact: /lib is
86 usually a symlink to /lib64 if you're running a 64 bit system, or /lib32 if
87 you're running a 32 bit system).
88
89 Similar to cleaning up the sources, we will clean up the moduels with a simple
90 but gratifying _rm -rf_ command.
91
92 rm -rf /lib/modules/4.2.{0,1,2,3}
93
94 That will clean up all the installed modules for the specified old kernel
95 versions (in this case, 4.2.0, 4.2.1, etc).
96
97
98 == Clean up Old Installed Kernels
99
100 The Linux Kernel installs itself to _/boot_. To see what you have for the
101 given version set (again, using the one from previous examples, run the
102 following command...
103
104 ls /boot/*-4.2.{0,1,2,3}
105
106 Again, a simple rm command will clean up these files.
107
108 rm -f /boot/*-4.2.{0,1,2,3}
109
110
111 And with that, you're done. All clean!
112
113
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115
116 [role="datelastedit"]
117 Last edited: {revdate}
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119 // vim:set syntax=asciidoc:
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